Technical Field
The present invention relates to a locking device, and more particularly to a locking device that is able to firmly tighten objects.
Description of Related Art
A locking device is utilized to tighten or loosen a fastener that is mounted to an object and is applied to fixtures such as a tool holder tightening fixture or a wrench. A conventional locking device adopts a keyway to engage the object or clamps the object by abutting. The conventional locking device assembled to a tool holder fixture has a frame, a collar body, a needle roller cage, multiple needle rollers, and a blocking plate. The collar body is mounted to the frame and has an inner peripheral surface defined in multiple concave recesses. The needle roller cage has multiple slots. The multiple needle rollers are respectively retained in the multiple slots and are respectively disposed according to the multiple concave recesses. The blocking plate is fastened to the collar body for retaining the needle roller cage and the multiple needle rollers inside the collar body.
When a tool holder is inserted into the collar body, the multiple needle rollers are abutted by the tool holder and are respectively pushed toward the multiple concave recesses. Then, the multiple needle rollers respectively abut against the multiple concave recesses, are clamped between the collar body and the tool holder, and are unable to rotate.
The conventional locking device locks the tool holder by the multiple needle rollers that are unable to rotate. However, each one of the multiple needle rollers contacts the tool holder in linear contact with a limited contact area. Therefore, the tool holder is very likely to shake in the collar body and cannot be firmly held by the conventional locking device.
To overcome the shortcomings of the conventional locking device, the present invention provides a locking device to mitigate or obviate the aforementioned problems.